Iran's president says his country will ask the six world powers at nuclear talks next week for imports of highly enriched uranium - material that the US fears Teheran wants to use to arm nuclear warheads.
Iran vehemently denies having nuclear weapons aspirations and President Mahmoud Ahmadinejad told The Associated Press on Tuesday that his country was seeking to buy uranium that is highly enriched - or near that level - to fuel a small research reactor.
He also made clear that Iran is seeking uranium that is enriched only to 20 percent - the threshold for the high-enrichment level but substantially below the 90 percent-plus grade needed for nuclear warheads.
"We are interested in purchasing it, and we'd like to offer that as an issue to expand discussions on the table for the next meeting," he told the AP on the sidelines of the UN General Assembly.
That request could put the US and its five negotiating partners in a bind at the Oct. 1 talks in Geneva. Until now, Iran has produced only low-enriched uranium, but it could use refusal of its request as a pretext to start producing high-enriched material.
Ahead of the negotiations, the foreign ministers of the six nations - the five permanent members of the UN Security Council and Germany - were meeting Wednesday on the sidelines of the General Assembly to discuss how to get Iran to stop uranium enrichment. Russian news agencies cited an official in the Russian delegation as saying Moscow does not rule out new sanctions against Iran over its nuclear program.
UN sanctions on Iran are meant to prohibit exports of sensitive nuclear material and technology. The international community is unlikely to give Iran enriched uranium closer to weapons-grade level at a time when it wants Teheran to stop enrichment.
In the enrichment process, uranium oxide is processed into uranium hexafluoride, which then is spun to varying degrees of enrichment, with low-enriched uranium used for nuclear fuel and upper-end high-enriched uranium used for nuclear weapons.
Security Council refusal to waive the sanctions could give Teheran a plausible reason to turn to its own facilities and produce high-enriched uranium.
Since Iran's program was discovered seven years ago, it has put thousands of centrifuges online to churn out enriched uranium. But the International Atomic Energy Agency says the more than a ton of enriched material it has amassed is all below the 5 percent level and well below the 20 percent highly enriched mark.
Still Iran's accumulation of well over 1,000 kilograms (2,200 pounds) of low-enriched uranium gives it more than enough material to produce enough weapons-grade uranium through further enrichment for one nuclear weapon.
Ahmadinejad, who has ruled out any compromise on enrichment at the Geneva talks, touched on the issue of enrichment levels in his comments to the AP, saying Iran was enriching only "to the grade of 3Â½ percent ... basically for our power plants."
Such low-enriched uranium can only be used for nuclear fuel - something Iran says it will need as it expands an ambitious civilian nuclear network.
But low-enriched uranium can be processed reasonably simply into higher grades, all the way up to weapons grade, stoking international fears of Teheran's ultimate aims - and three sets of Security Council sanctions since 2006 meant to crimp Iran's program.
Teheran's small and creaky research reactor has not figured highly in international concerns. But - unlike Iran's planned reactor network that Teheran says will be fueled on enriched uranium below 5 percent - it runs on fuel enriched to just below the 20 percent, highly enriched threshold.
In announcing the import request, Ahmadinejad suggested the more than 30-year-old 5-megawatt reactor, which Teheran says is needed for medical and scientific research, had used up its reserves of 19.75-level fuel, adding "we cannot produce that (level) at this moment."
"It appears that fuel is running out," said David Albright, whose Washington-based Institute for Science and International Security has closely tracked Iran's nuclear program for signs of covert proliferation. "But they can't buy any because of the Security Council sanctions, so they would need an exemption."
Such a waiver is unlikely, said a senior Western diplomat whose country is on the 35-nation IAEA board and who spoke on condition of anonymity because he was not authorized to comment.
But refusal could provide Iran with a pretext to reconfigure its enrichment program at the central city of Natanz to move to the next level - producing uranium at or near the highly enriched 20 percent level.
Albright said even producing the relatively small amount of more highly enriched material that the Teheran reactor would need would be of concern because it would increase Teheran's know-how - and make producing weapons-grade material easier, should Iran choose to go that route.
"The international community is in a bind," he said. "It's not in their interest to make exemptions to the (U.N) resolutions that Iran refuses to abide by.
"At the same time, they don't want enrichment at Natanz to go above 5 percent."
Of additional concern, he said, would be the fact that the Iranians would be expected to turn any more highly enriched fuel into uranium metal, further perfecting that technology.
He said the Teheran reactor uses enriched uranium metal as fuel. But weapons-grade uranium is also turned into uranium metal - and then shaped into warhead form.